Hydrogen oriented underground coal gasification for Europe : environmental and safety aspects (HUGE2) : final report

The objective of the project was to demonstrate in the PDU scale the feasibility of safe and environment friendly Underground Coal Gasification for hydrogen-rich gas production. The in-situ UCG process energy efficiency was 70% with the maximum hydrogen content in product gas of approximately 48% proving the V-shape configuration of gasification channel effective, but also creating specific operational problems. Phenol and benzene derivatives, PAHs and N-heterocycles, ammonia, heavy metals, cyanides and sulfates were the main liquid by-products contaminants, of high and lasting eco-toxicity in respect to aquatic biota. Mathematical models of gaseous and liquid contaminants' propagation in strata indicated the pore size, tortuosity and rocks' porosity as the factors influencing the most the gas migration and textural characteristics of rocks, sorption capacity and contaminants' solubility in groundwater affecting the propagation of contaminants in the liquid phase. Methods and materials for filling of post-gasification voids and their influence on the release and migration of contaminants were assessed and recommended. A risk management strategy, following ISO31000 principles was applied. The environmental monitoring system and the decision support system were developed. Activated carbon and zeolite proved to be the most effective materials to be applied in permeable reactive barriers for the in-situ remediation of the potentially contaminated aquifers.